A number of researchers in the Department of Biochemistry and Molecular Biology at the University of Chicago have defined needs for X-ray diffraction analysis in their work. The direction of modern molecular biological research is such that the use of X-ray diffraction is no longer the province of X-ray crystallographers, but rather it is rapidly becoming a tool for general research into the nature of structure- function relationships. With the advances in such diverse techniques as gene manipulation, gene expression and X-ray data collection, elegant and rapid molecular experiments can be planned and executed. No modern research institute can neglect the contributions structural biology can make to biomedical research. In the Department of Biochemistry and Molecular Biology, we are expanding our efforts into structural biology to support our active research programs in molecular enzymology, protein folding, membrane protein structure, time-resolved crystallography and protein engineering. We can not rely on photographic data collection methods for much of our work. It is thus necessary to acquire reliable X-ray equipment to satisfy our requirements for rapid and accurate data collection. Our aim is to rebuild the X-ray facility to provide the resources for crystal characterization and for crystal data collection by position-sensitive electronic detectors. We are requesting funds to purchase an Enraf Nonius FAST area detector plus a crystal cooling device. Our research programs would benefit from the "in-house" availability of a good facility for X-ray diffraction experiments.